Algorithms Worksheet - KS3 - Intermediate

Algorithms worksheet for Key Stage 3 / Year 7-9 (Ages 11-14). Intermediate level computing practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Computing•Key Stage 3 / Year 7-9 (Ages 11-14)•Algorithmsintermediate

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Exploring Algorithms in Computing

Key Stage 3 / Year 7-9 (Ages 11-14) - Intermediate Level

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Instructions: This worksheet introduces you to the fascinating world of algorithms. You'll explore different types of algorithms, understand their applications, and practice problem-solving using these concepts. Follow the instructions carefully for each activity and use the space provided to write your answers.

Understanding Linear Search

Learn about the linear search algorithm, which checks each element in a list sequentially until the desired element is found or the list ends. Use the example list to find the target number and explain the steps taken.

List: [3, 7, 1, 9, 5, 8, 2]

Target: 9

Describe the steps of the linear search to find the target number.

Exploring Binary Search

Binary search is an efficient algorithm for finding an item from a sorted list by repeatedly dividing the search interval in half. Use the sorted list provided to find the target number using binary search.

Sorted List: [1, 2, 3, 5, 7, 8, 9]

Target: 5

Explain the steps of the binary search algorithm to locate the target number.

Bubble Sort Algorithm

Bubble sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order. Sort the given list using bubble sort and describe each pass.

Unsorted List: [4, 2, 9, 1, 5]

Perform bubble sort on the list and describe each pass.

Understanding Merge Sort

Merge sort is a divide-and-conquer algorithm that divides the list into halves, sorts them, and then merges them back together. Apply merge sort to the list and explain the process.

Unsorted List: [6, 3, 8, 5, 2]

Use merge sort to sort the list and describe the steps involved.

Insertion Sort Practice

Insertion sort builds the final sorted array one item at a time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort. Sort the list using insertion sort.

Unsorted List: [10, 3, 7, 4, 8]

Perform insertion sort on the list and describe each step.

Algorithm Efficiency

Understand Big O notation, which describes the performance or complexity of an algorithm. Match each algorithm with its Big O notation.

🫧 --- O(n²)

Match each algorithm to its Big O notation.

Algorithm Application

Consider scenarios where different algorithms might be applied. For each scenario, choose the most appropriate algorithm and justify your choice.

1. Searching for a book in a sorted library catalogue.

2. Sorting a small list of student names.

3. Finding a specific contact in a phonebook app.

Algorithm Design Challenge

Design a simple algorithm to solve a real-world problem. Describe the problem, outline the algorithm, and explain how it solves the problem efficiently.

Describe a real-world problem and design an algorithm to solve it. Explain your algorithm and its efficiency.

Answer Key

Activity 1: Steps include checking each element until 9 is found

Activity 2: Divide list, check middle, adjust search range until 5 is found

Activity 3: Passes include swapping adjacent elements until sorted

Activity 4: Divide list, sort halves, merge sorted halves

Activity 5: Insert each element into the correct position in the sorted part

Activity 6: Linear Search: O(n); Binary Search: O(log n); Bubble Sort: O(n²); Merge Sort: O(n log n)

Activity 7: 1. Binary Search; 2. Insertion Sort; 3. Binary Search

Activity 8: Student's own algorithm and explanation